Systems and methods for generating energy using a hydrogen cycle

ABSTRACT

Systems and methods for continuously generating electric power using a renewable energy power source to continuously generate electrical energy are disclosed. An illustrative embodiment includes transmitting electrical power from the renewable energy power source to an electrolyzer to produce hydrogen gas, storing the hydrogen gas in a storage facility until production of power from the renewable energy power source drops below a predetermined threshold, and activating a secondary power generation system that converts the stored hydrogen to electrical energy. The stored hydrogen may be converted to electrical energy using a gas turbine generator or a fuel cell. The system further includes a reverse osmosis subsystem for purifying water for use in the electrolyzer and optional systems for providing the purified water to a community and for using the produced electricity to treat waste water to generate treated water that may be purified and supplied to the electrolyzer.

TECHNICAL FIELD

The present invention generally relates to a large-scale renewableenergy production processes that use a renewable energy source forgenerating hydrogen gas that may subsequently be used in a gas-turbinepower generation system that is co-operated with the renewable energysource.

BACKGROUND

While there is a desire on the part of many consumers to acquire theirenergy needs solely from a renewable energy source, such as wind energyor solar power, these energy sources may be lacking incost-effectiveness and reliability due to the presence of inefficienciesin power existing production systems or natural variations in theavailability of sunlight and wind for power production.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments are described in detail below with reference tothe attached drawing figures, which are incorporated by reference hereinand wherein:

FIG. 1 is a block diagram showing a system and related processes forgenerating renewable energy and hydrogen gas, and using the renewableenergy and hydrogen gas to generate electric power;

FIG. 2 is a block diagram showing a cogeneration system that uses gasturbines to generate electric power;

FIG. 3 is a block diagram showing a hydrogen production and waterpurification system that uses electric power and water to generatehydrogen gas and purified water; and

FIG. 4 is a block diagram showing a water treatment system that operatesin conjunction with the aforementioned systems.

The illustrated figures are only exemplary and are not intended toassert or imply any limitation with regard to the environment,architecture, design, or process in which different embodiments may beimplemented.

DETAILED DESCRIPTION

In the following detailed description of the illustrative, non-limitingembodiments, reference is made to the accompanying drawings that form apart hereof. These illustrative embodiments are described in sufficientdetail to enable those skilled in the art to practice the invention. Itis understood that other embodiments may be utilized and that logicalstructural, mechanical, electrical, and chemical changes may be madewithout departing from the spirit or scope of the invention. To avoiddetail not necessary to enable those skilled in the art to practice theembodiments described herein, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is not to be taken in a limiting sense, and the scope of theillustrative embodiments is defined only by the appended claims.

According to an illustrative embodiment, a process for producing andapplying renewable energy incorporates at least three technologies:renewable power such as (for example) solar power and wind power, gasturbine power, and hydrogen electrolyzers. None of the threetechnologies is capable on its own of providing continuous power whileusing only renewable energy sources. For example, most gas turbines burnnatural gas, and most renewable energy is derived from non-constantenergy sources such as wind, sun, or tides. With this process, a stableand continuous source of power can be guaranteed to a specific user orthe grid with zero carbon emissions and using only renewable energy todrive the system.

The current electrical grid is set up to rely on continuous power anddoes not respond well to dips and major fluctuations in demand. Further,recent government mandates in the U.S. and in other countries call forincreasing percentages electric power to be provided to the grid fromrenewable sources. Many renewable sources, however, are inherentlyunstable sources of electricity. According to the illustrativeembodiments, systems and methods that involve a renewable energy,hydrogen cycle system are disclosed that reduce instability typicallyassociated with renewable energy sources (also referred to as“renewables”) and provide clean power at competitive whole sale rateswithout interruption.

Referring now to the figures, an illustrative system is described withregard to FIG. 1. As shown in FIG. 1, in illustrative system forproducing continuous electric power from renewables 100 includes arenewable energy source 102. The renewable energy source 102 may be anysuitable renewable energy source, including without limitation a windfarm, a solar panel farm, or a tidal hydroelectric generator. Therenewable energy source 102 generates electric power when energy isavailable. For example, in the case of solar power, solar energy isavailable when the sun provides light of a sufficient magnitude thatmakes it efficient to produce electric power using solar panels.Similarly, wind energy may be extracted from the atmosphere when thewind blows at a sufficient magnitude to power a windmill or windturbine. Hydroelectric generators powered by title energy may similarlyextract energy from ocean tides as the sea level rises and falls at thesite of the generators. Energy harvested from the renewable energysource 102 is transmitted to a transformer substation 104 for conversionto an appropriate voltage, and the transformed electricity 124 isconveyed to a control room or switching station 106. During times ofpeak energy production or when adequate energy is stored in other partsof the system, the electric energy is provided to a transformersubstation interconnect 108 and supplied to the public for use via agrid 110. Alternatively, the energy may be transmitted to an alternatetransformer substation 112 and stored at or provided to a userproduction facility 114 for use at the site of the system 100.

An embodiment, the electric energy may also be provided from the controlroom/switching station 106 to an on-site (optional) water treatmentsystem 122 and to a hydrogen production system 120. In an embodiment,the system 100 uses purified water to operate efficiently, therefore thesystem may include mechanisms for treating wastewater, sea water, orwell water for use as feed water in an electrolyzer. According to anillustrative embodiment, if a domestic water source is needed in thevicinity of the plant, the system may include a reverse osmosis systemthat can be scaled to supply domestic need for water in the community.As referenced herein, a “community” is generally understood to be acommunity that is served by a commercial, military, or industrial powerproducer, such as a village, a city, a military base, or an industrialplant, such as a manufacturing facility.

Energy provided to the hydrogen production system 120 may be provideddirectly to the hydrogen production system 120 and used to producehydrogen 126 and oxygen from a water source using electrolysis. In anembodiment, the provided energy may be transmitted directly to thehydrogen production system 120 without the use of batteries as a storagemedium. The produced hydrogen 126 is conveyed to a hydrogen storagesystem 118, and may subsequently be supplied to a gas turbine powergeneration system, such as the cogeneration system 116, which isdescribed in more detail with regard to FIG. 2. When it is not optimalto produce power from renewables because, for example, the sun is down,the tide is not changing, or there is no wind, the system 100 piecesceases using renewable power to supply energy to the grid and activatesor increases power generation from the cogeneration system 116. When thecogeneration system 116 is activated, hydrogen 126 that was created andstored during time periods in which there is an overabundance ofrenewable energy is supplied to the cogeneration system 116 toefficiently generate electric power that is subsequently supplied to thecontrol room/switching station 106 and distributed to the userproduction facility 114 or to the grid 110, as described above.

In an illustrative embodiment, to provide continuous 24 hour power withrenewable variable energy, the system 100 uses hydrogen as a storagemechanism to store excess energy generated from the renewable energysource 102. As noted, hydrogen is created through electrolysis whereelectricity from the renewable energy source 102 is used to break waterinto its component hydrogen and oxygen atoms. The stored energy in theform of hydrogen is then burned in gas turbines of the cogenerationsystem 116 to produce electricity when the renewable energy source isnonfunctional. In an embodiment, the system 100 is also capable ofproducing domestic water and potentially reclaiming wastewater as well.As such, the system has the ability to provide power, purified freshwater, and water treatment.

The renewable energy source 102 may be a non-constant, renewable energypower generator. Any source or combination of renewable energy may beused, including wind, solar, tidal, or any other as yet unknown methodof harvesting energy from renewables that produces variable electricpower. More stable forms of renewable energy, such as hydropower andgeothermal power, may also be used.

In an embodiment in which the renewable energy source 102 is a windfarm, the wind farm may include utility scale windmills or wind turbineswith attached generators to produce power. Companies such as Siemens andG.E. make wind turbines suitable to utility scale applications. 500 KWwind turbines or smaller may be used for low demand applications and 10MW or higher out wind turbines may be used for high demand applications.The Wind Farm is sized using two factors, energy demand, andproductivity. Demand on the farm is created from three sources: thehydrogen production system 120 that uses electricity to store energy asgenerated hydrogen, electricity provided to end users via the userproduction facility 114, and electricity sales to the grid 110.Productivity is generally expressed as the average amount of wind thatthe farm receives in a given month.

In an embodiment in which the renewable energy source 102 is a solarfield, field may include either concentrated photovoltaic (CPV) orthermal voltaic (TPV) solar arrays. As referenced herein, a concentratedphotovoltaic array is an array made up of solar panels that magnify andconcentrate solar radiation at a focal point where it can be absorbedand converted to electricity. Similarly, a thermal voltaic solar arrayis an array made up of solar panels that absorb radiant energy from thesun and convert it to electricity. In an embodiment, the solar fieldincludes double axis trackers, such as those developed by MST to theirincrease the efficiency of the array. It is noted that CPV arrays aresuitable for areas that receive intense sunlight where cloud cover andinclement weather is minimal Generally, CPV technology reduces the landarea used for energy production to an estimated 2.5 to 2.96 acres permegawatt (MW), depending on topography. TPV is better suited fornon-optimal solar locations having higher average cloud cover. TPVusage, however, make way to a larger footprint for the solar field, atapproximately 3.6 acres per MW. At any rate, the size of the solar fieldis determined by two factors: energy demand and the expected amount ofsunlight (weather). Again, demand on the solar field may be created fromthree sources: the hydrogen production system 120, the user productionfacility 114, and the grid 110.

Water can be used as a hydroelectric power source in a variety of waysthat would facilitate system operations. In addition, ground water, seawater, domestic water, and even reclaimed water can all be used as aprimary source for both cooling and hydrogen feed water. In anembodiment, all water, regardless of its source, may be processedthrough a reverse osmosis facility to remove any impurities that mightdamage system equipment. In the event a domestic water supply is used,for example, all chlorine and fluorine are removed prior to usage toprevent damage to membranes in the reverse osmosis facility.

The system 100 plant can be designed to address a community's power andwater demands. For example, the reverse osmosis plant can be sized toinclude domestic water production as well as water for all electrolysisand cooling for all portions of the system 100. In the event thatdomestic water is needed additional water storage may also be taken intoaccount.

According to an illustrative embodiment, hydrogen is produced by ahydrogen generator generation system 120, which is described in moredetail with regard to FIG. 3. In some embodiments, the hydrogengenerator produces hydrogen through electrolysis. In such an embodiment,an electrolyzer 304 receives power 324 from a renewable energy source,as described above. The electrolyzer 304 uses electrolysis, the processby which low voltage electricity is used to break apart a water moleculeinto hydrogen and oxygen, to make hydrogen using water received from awater source 310 and the electric power 324 received from a renewableenergy source. In an embodiment, fresh water electrolysis yields onlyhydrogen and oxygen, with no other byproducts. The electrolyzer 304exchanges cooling water 308 with a cooling reservoir 302. And providedhydrogen gas for storage and a hydrogen tank 316. The hydrogen tank 316may be coupled to a hydrogen storage facility, such as tanks in thehydrogen storage facility 118 of FIG. 1.

In an embodiment, water may be received from a water source 310, whichmay be a pump or well that may provide water to a reverse osmosis system306 be a series of valves 312, 314. The valve 312 may be an optionalautomatic valve on a domestic water source that is controlled by floatswitches and a storage tank, and a second valve 314 may be a check valvethat prevents backflow, which is instead diverted to a backwash pond318.

An embodiment, the electrolyzer 304 is a utility scale electrolyzer thatgenerate hydrogen. For example, the electrolyzer 304 may be an alkalineelectrolyzer capable of producing, for example, 760 normal cubic metersof hydrogen gas an hour at a pressure of up to, for example, 450 PSI (32bar). In another embodiment, the electrolyzer 304 may be capable ofproducing, for example, 500 normal cubic meters at pressures of no morethan 1 bar. The electrical demand of an electrolyzer 304 that producesapproximately 760 normal cubic meters of hydrogen gas an hour at apressure of up to 450 PSI may be in the range of 4.3 to 4.6 KWh pernormal cubic meter of hydrogen produced, while an electrolyzer 304 thatproduces 500 normal cubic meters at a pressure of 1 bar may useapproximately 4.1 to 4.3 KWh per cubic meter of hydrogen produced.

It is noted that water has two uses in the electrolyzer 304. Purifiedwater received from a water storage tank 318, which is purified by areverse osmosis system 306 may be used as a hydrogen source. Inaddition, cooling water 308 received from a cooling reservoir 302 isused to cool the electrolyzer 304 to prevent overheating. In anembodiment, the electrolyzers 304 use 40 liters of cooling water pernormal cubic meter of hydrogen gas produced. The electrolyzers 304 mayalso use approximately 0.85 liters of feed water from the peer fightwater tank 318 per normal cubic meter of hydrogen produced.

According to an illustrative embodiment, the electrolyzers' cells havean expected life of 10 to 15 operating at full production. In anembodiment in which the electrolyzers 304 are operated an average of 6to 8 hours per day, the lifespan of the electrolyzers' cells may betripled.

Hydrogen 322 may be exported from the hydrogen tank 316 to a hydrogenstorage system, such as the hydrogen storage system 118 of FIG. 1.Referring again to FIG. 1, the hydrogen storage system 118 includes highpressure storage tanks, which may be pressure vessels rated to 1500 PSI(105 bar). Thus, prior to entering the high pressure vessels of thehydrogen storage system 118, the pressure of the hydrogen may be raisedfrom, for example, 450 PSI (32 bar) to 1500 PSI (105 bar), to maximizeuse of the storage tanks by minimizing the needed storage volume. Sizingthe hydrogen storage system 118 may be a function of weather andelectrical demand. For example, using weather data, (in an embodiment inwhich the renewable energy source is a solar array) we may determine the100 year maximum of consecutive cloudy days, which is the number of daysthat hydrogen would be used to run the gas turbine facility on a 24 hourbasis while the solar field is non-functional. In such an embodiment,the hydrogen storage system 118 may be sized to store the amount ofhydrogen needed to power the gas turbine facility 116 for the determinedmaximum number of cloudy days.

An embodiment, high pressure gas lines used in the system 100 will bedouble walled with hydrogen detection equipment installed to maintainsafety. In addition, valves to each tank may include automatic shutoffsystems with automatic pressure loss sensors to isolate any tank thatmight develop a leak.

According to an illustrative embodiment, gas turbines will use hydrogengas instead natural gas as a fuel to function as gas turbine powergenerators 116. Studies have already been done using hydrogen as a gasturbine fuel with Siemens gas turbines. The report in the Journal ofEngineering for Gas Turbines and power, January 2005 Vol. 127 titled“Using Hydrogen as Gas Turbine Fuel”, which is herein incorporated byreference, indicates that the Siemens turbines will compensate forhydrogen as a fuel with only minor adjustments. While Siemens isdiscussed by way of example, any Gas Turbine that is capable of burninghydrogen will work.

Turbine sizing may be determined by overall energy demand with aprojected minimum size demand of, for example, 20 MWh. There may bevirtually no limit on demand, however, as multiple large turbines can beused in parallel. Gas turbines having output capacities of, for example,up to 300 MW or more may be used.

In an embodiment, the gas turbines are part of a cogeneration system116, which is an illustrative system for converting the hydrogen gas toelectric power. As such, it is noted that any suitable mechanism forconverting hydrogen gas to electric power may be used. An illustrativecogeneration system is described with regard to FIG. 2.

According to an illustrative embodiment, the co-generation system 116includes one or more gas turbines 201, such as primary turbine generator202 and secondary turbine generator 204. The gas turbines 201 receivehydrogen 216 from a hydrogen storage facility and convert the hydrogento electric energy 214 that may be provided to the grid in addition toheated exhaust that may be provided to a heat exchanger 206 tofacilitate the recovery of additional energy. The size and type of theco-generation system 116 used is determined by the heat rate of the gasturbine(s) being used. For example, on smaller installations, lowtemperature steam turbines 209, including primarily temperature steamturbine 208 and secondary low temperature steam turbine 210, which maybe Pratt & Whitney Turboden generators that recover exhaust through heatexchangers 206 and provide up to an additional, for example, 12 MW perunit installed can be used. Depending on the size of the gas turbines201, multiple units may be attached to each gas turbine. The steamturbines 209 and be coupled to a cooling tower 212 to enhance energyrecovery. Larger installations can use a high pressure steam turbine asa cogeneration unit. Water vapor that is recovered from the gas turbinesystem may be recovered and repurposed for provision to the communityas, for example, irrigation water or as a potable water source.

NOX emissions in such a system may be verified to be approximately, forexample, 40 PPM or less when using hydrogen as a fuel. This level NOXemissions may not be a significant factor but in the event that theturbine chosen has significant NOX emissions, a NOX scrubber plant canbe constructed to reduce NOX emissions to an acceptable level.

In another embodiment, it the gas turbine generators may be replaced byfuel cells. Such fuel cells may generally include an anode, a cathode,and an electrolyte that are constructed to allow charges to move betweenopposing sides of the fuel cell. The migration of charged particlesresults in a chemical decomposition of the fuel and functions as amechanism for extracting chemical energy to produce electricity. Anysuitable fuel cell may be used in such an embodiment, including, forexample, a proton exchange membrane fuel cell (PEMFC), an alkalineelectrolyzer, a phosphoric acid fuel cell, a solid oxide fuel cell, amolten carbonate fuel cell, a tubular solid oxide fuel cell. In anembodiment, the fuel cell may customized for utility scale electricityproduction.

Referring again to FIG. 1, according to an illustrative embodiment, acontrol room 106 includes a control system were switching room that isresponsible for day to day plant operation, including internal plantelectricity distribution; electricity distribution to grid and or enduser; hydrogen production and hydrogen storage; gas turbine operation;reverse osmosis system operation; and safety monitoring and coolingsystem monitoring. In an illustrative embodiment, the control room 106includes a control system that implements an automated process foractivating and deactivating the systems described. For example, thecontrol system may determine that the maximum amount of hydrogen hasbeen stored, and divert all energy produced by the renewable energysource 102 to the grid 110 until it becomes necessary to generateelectricity using hydrogen. In another embodiment, the control systemmay balance operation of the gas turbine generator with output of therenewable energy power source to level-load power output to an end useror the grid. In another embodiment, the control system may determinethat the amount of stored hydrogen is equal to a predetermined amountthat corresponds to the expected amount of hydrogen needed for aparticular time of year (for example, less hydrogen storage may benecessary at the beginning of the summer then at the end of the summeror the fall when cloudy days are expected in the near future). In suchan embodiment, once the expected amount of hydrogen is stored, thecontrol system may divert all additional energy produced by therenewable energy source 102 to the grid 110 until it becomes necessaryto generate electricity using hydrogen again. Similar processes may beinvoked for wind and tidal systems, which may be optimized based onforecasted amounts of wind and lunar cycles that affect the magnitude oftidal sea level changes. Thus, in an illustrative embodiment, thecontrol room 106 performs automated or near-automated control andmonitoring of the systems and processes described herein.

Referring again to FIG. 3, an illustrative embodiment three methods ofcooling may be used for cooling the electrolyzers 304 and hydrogencompression: cooling towers, chillers, and cooling ponds. Each systemmay be selected for site specific rationale in consideration of, forexample, temperature, humidity and water availability. Cooling towersmay be the most efficient but use large amounts of water and may onlyreach peak efficiency in arid climates. Chillers have a minimal waterusage guidelines but use a noticeable amount of electricity andtherefore may be more suitable for high wind/solar, low water climates.A cooling pond uses no electricity and can be designed to providepotential ecological benefits to the area it is installed in, but is nottypically as efficient as a cooling tower. A cooling pond, however, mayalso be selected to minimize capital costs.

The following portion of the description describes the operation of anillustrative embodiment of the system in which the renewable energysource 102 is a solar field. According to the illustrative embodiment,during daytime operation, power from the solar field is collected at asolar substation where voltage is increased in preparation fordistribution. The facility control room 106 may determine where power isneeded in the 100. In the event that there is excess power from thesolar field, it may be sold to the grid 110. The control room 106determines which elements of the system 100 are currently active, adeach system element can be separately activated and run independently bythe control room 106. Based on the determination of the control room106, power for each subsystem is then routed from the solar substationto the active system facilities.

According to an illustrative embodiment, hydrogen production begins withthe water produced by the reverse osmosis system 306, which may also bereferred to as a reverse osmosis plant. In the embodiment, non-treatedwater is pumped to primary storage for use in the reverse osmosis plant306. In the event domestic water is used, all fluorine and chlorine areremoved prior to use in the reverse osmosis facility to avoid damagingthe membranes. Two days of reserve non-treated water may be stored inthe event of an interruption in water supply. After treatment in thereverse osmosis facility, the water is pumped to secondary storage. Twodays of secondary storage may also be maintained. All storage ismaintained automatically by the control room via float systems in thestorage tanks. Water to be used by the electrolyzers is routed viaautomatic valves operated by the control room. As part of theelectroloysis process, cooling water is supplied at a rate of, forexample, 40 liters per normal cubic meter of hydrogen gas produced or0.3 gallons per normal cubic foot of hydrogen gas produced. As with thefeed water, cooling water may also be activated via automatic valves anda pump system. Cooling water is circulated through the electrolyzers 304and routed through a cooling process that reduces cooling watertemperature by, for example, 36 degrees Fahrenheit. According to anillustrative embodiment, a cooling pond is chosen as a cooling reservoir302 in favor of chillers or cooling towers to minimize costs. Thecooling pond may be designed to be functional as well ecological. In anembodiment, a pond of 16 acres with a depth of six feet would besufficient for all cooling needs. This calculation is based on anambient temperature of 85 degrees with 20 percent average relativehumidity. Water circulation through the electrolyzers 304 occurs onlyduring hydrogen production. During summer months, it is noted that theelectrolyzers 304 may only operate for 8 hours a day due to decreaseddemand, thereby lowering cooling requirements relative to the coolingreservoir 302 during the hottest times of the year.

The electrolysis process may yield only hydrogen and oxygen with noother by-products. Hydrogen produced may have a purity of 99.8% and thusneed no further refinement to be used as a fuel by the gas turbinegenerators 116. Oxygen produced by the electrolyzers 304 has a similarpurity and may also be stored and marketed if not it is released backinto the atmosphere. In an embodiment, the hydrogen is compressed in theelectrolyzer, which may be a high-pressure electrolyzer that compressesthe produced hydrogen to, for example, 450 PSI (32 bar) for storage. Thecompressed hydrogen may then be transported to the hydrogen storage areawhere it may be further compressed for more efficient storage. In anembodiment, prior to entering storage tanks, the pressure of thehydrogen gas is increased to 1500 PSI (105 bar) in preparation forstorage. The storage field may include multiple high pressure gasstorage tanks isolated from each other and connected by a valved headersystem. The valved header system allows the control room to pressurizeeach tank individually and monitor the pressure in all tanks constantly.As noted above, all high pressure piping may be double walled withhydrogen gas sensors between walls to detect any leaks. In criticalareas parallel system of piping may be installed to ensure safe andcontinuous plant operations. The overall size of the hydrogen storagefield may be determined by weather and demand, as noted previously.

According to an illustrative embodiment, hydrogen from the storage tanksis routed to the gas turbines to produce electricity when the renewablesource 102 is not sufficiently productive. Hydrogen may be drawn fromany tank. A master control valve regulated by the control room 106 maydetermine when gas is allowed to flow to the turbines 116. The Gasturbines 116 utilize hydrogen gas at approximately, for example, 400 PSI(30 bar). To facilitate this decrease in pressure from the storagepressure, a regulator and pump system are inserted between the hydrogenstorage 118 and the gas turbines 116 to maintain the appropriateconstant pressure to the turbines 116. The regulator reduces thepressure to, for example, 400 PSI (30 bar) in the event that the storedgas pressure is higher. When the storage tank pressure is lower than 400PSI (30 bar), an additional compression pump is used to maintainoperating pressures. Each turbine has its own automatic valve system toallow independent operation controlled by the control room 106. Turbineoperation only occurs when the solar field or other renewable source 102is inactive due to night or weather. Correspondingly, hydrogenproduction only occurs while the solar field or other renewable source102 is active and therefore generally does not occur when the turbinesare active.

According to an illustrative embodiment, the turbines operate in thesame manner as a jet engine. Fuel is burned in a combustion chamber. Gasrapidly undergoes thermal expansion, greatly increasing the pressure.The exhaust gases are used to turn a multiple bladed turbine thatcreates rotational kinetic energy. The rotational energy is transferredthrough a drive shaft to an electrical generator. The excess heat fromthe exhaust gasses is captured and sent to a heat exchanger for use inthe co-generation turbines. In a case study, a turbine produces 289.9pounds per second of exhaust at 1011 degrees F.

According to an illustrative embodiment, the co-generation turbinesoperate by using a thermal oil in a closed hydraulic system to generateadditional rotational energy that is captured by an electricalgenerator. The combined energy from both generators is collected at anelectrical sub-station where it is prepared for distribution to the enduser production facility 114 or grid 110.

As shown in FIG. 1, an illustrative system 100 that applies the abovedescribed process may also include a water treatment system 122. Thisfacility is optional and decreases the demand for water while alsoproviding another service to the community proximate the system 100. Asdescribed with regard to FIG. 4, such a water treatment system 122 mayinclude a control building 416 that controls and powers the watertreatment process. As such, the control building 416 may receive powerfrom the renewable energy source 102 or gas generators 116 of FIG. 1.The water treatment system 122 may receive wastewater 420 that issupplied to the primary clarifier 402. The water is routed through aseries of a primary clarifier 402, trickling filter 404, secondaryclarifier 406, trickling filter 404, sand filter 408, and a chlorinecontact filter 410, at which point the treated water 418 is suitable fortransmission to the hydrogen production system 120 where it may befurther purified and used for feed water. Particulate may be extractedfrom the wastewater 420 from the primary clarifier 402 and secondaryclarifier 406. The particulate may be diverted to an anaerobic digester412 and subsequently to sludge beds the 414 that may ultimately beharvested to produce fertilizer, thereby providing an additionalresource to the community.

Referring again to FIG. 1, it is noted that the systems and processesdescribed above may be executed in accordance with a suitablemethodology. For example, according to an illustrative embodiment, asolar-hydrogen (or renewable energy-hydrogen) cycle may be considered amethod by which alternative green energy can provide 24 hour power 365days a year to a specific user or to the grid 110. The system 100 uses arenewable source 102 to produce hydrogen gas that will operate gasturbines 116 when the renewable source is inactive. Renewable source 102and plant design is site specific and depends upon the amount ofproduction of the renewable source 102, the type and amount of wateravailable, the location of the grid 110 and interconnect, and theminimum amount of continuous 24 hour power to be produced.

According to an illustrative embodiment, the system 102 operates withthe renewable source 102 providing power for water purification,hydrogen production, hydrogen storage, and other plant processes as wellas providing the continuous power to be generated to the end user or thegrid 110. Therefore, the renewable source 102 may be sized to produceenough power to produce hydrogen during that portion of the year whenthe renewable source's 102 productivity is lowest. For modeling purposesthe “average renewable day” for every month may be determined During theshortest “average renewable day” of the year, hydrogen production isslightly more than is needed to operate the gas turbines during theprojected renewable energy source downtime. The excess hydrogen is sentto a storage facility 118 for use when the renewable energy source 102is inactive. Storage volumes are determined by evaluating frequency thatthe renewable energy source is non-productive during the shortest“average renewable day”. A safety factor, for example, may be applied tothe average expected downtime of the renewable energy source.

According to an illustrative embodiment, the hydrogen demand isdetermined by the amount of power needed to maintain “stated plantoutput” while the renewable energy source is non-operational. The time(expressed by T), the solar field may be non-operational is determinedby subtracting the “average renewable day” of any given month from 24hours. As referenced herein, the average renewable day is the averagenumber of hours per day in a given month that the renewable energysource produces renewable energy. Power is produced during down time ofthe renewable energy source 102 by the gas turbines 116, which burnhydrogen to produce power. The amount of hydrogen used by the turbinesas fuel is determined by the heat rate of the turbine. This number isexpressed in BTUs per KWh and varies from generator to generator. Todetermine the total number of BTUs used to operate the gas turbine (TH)the equation, HR×T=TH is used. Here, HR is the heat rate, T is time, andTH is the total heat in BTUs. The power from the co-generation units,however, may also be taken into consideration. To do this, the equationTH/TP=RHR, where TH is the total heat from the gas turbines in BTUs, TPis total power produced by both the gas turbine and the co-generationsystem, and RHR is the revised heat rate. The revised heat rate ismultiplied by the LHV of a normal cubic foot of hydrogen gas todetermine the amount in normal cubic feet hydrogen needed to produce aKWh of power. Here, LHV is defined as “lesser heating value,” which isthe amount of heat that burning a compound (such as hydrogen) willyield. This number is multiplied by the “stated plant output” and T todetermine the average hydrogen demand per day for the given month.

In an embodiment, the renewable power source size is determined by theamount of power necessary to produce the hydrogen through theelectrolysis process. In the case of a suitable solar panel type, forexample, the electrical demand is given as, for example, 4.3 to 4.65 KWhper normal cubic meter of hydrogen. Here, it is necessary to convertnormal cubic meters to normal cubic feet, which is done by multiplyingby a factor of 35.31. A result of 4.3 to 4.65 KWH per 35.31 normal cubicfeet is obtained, which simplifies to a result of 8.21 to 7.59 normalcubic feet per KWh. The more conservative number of 7.59 normal cubicfeet per KWh may be chosen when determining the power demand to generatehydrogen. Thus, the number of cubic feet of hydrogen used on an averageday in a given month may be multiplied by the 7.59 KWh per cubic foot todetermine an average daily power requirement per month for the solarfield to generate. The field may be sized to the highest average dailyhydrogen power used plus this demand for “stated plant output”.

According to an illustrative embodiment, water requirements are based onhydrogen demand and cooling requirements. As stated above, exemplaryelectrolyzers use 0.85 liters of feed water per normal cubic meter ofhydrogen produced. Converting to the English scale yields 6.36 gallonsper 1000 normal cubic feet of hydrogen. A feed water usage guideline isthen derived by dividing 6.36 gallons per 1000 normal cubic feet ofhydrogen into the average daily hydrogen demand. Other suitableelectrolyzers use, for example, 40 liters per normal cubic meter ofcooling water, or about 0.3 gallons per normal cubic foot of hydrogenproduced. This water is cooled by 38 degrees Fahrenheit. In anembodiment, a cooling pond is used that primarily functions by usingevaporation as a cooling method. The water to be used from the pond isdetermined by series of equations which can be found in “Surface HeatLoss From Cooling Ponds” by Ryan, Harleman, and Stolzenbach (WaterResources Research, Jul. 9, 2010), which is herein incorporated byreference. The total daily water usage need is the pond make up waterplus the hydrogen electrolyzer feed water.

As described previously, the control room is responsible for ensuringday to day plant operations and for executing computer programs that mayprovide automatic functioning of the related systems. According to anillustrative embodiment, a single unified program automates all or aportion of the process. The program may accommodate operation when therenewable power source is active and when it is non-functional. Duringdaytime operation, the control room monitors power produced from therenewable energy source, the control room distributes power from therenewable energy source 102 internally and potentially to the grid 110,monitors cooling temperatures, regulate hydrogen production, andcontrols hydrogen gas distribution into the storage facilities as wellas all safety monitoring to ensure that there are no hydrogen leaks.

According to an illustrative embodiment, if the renewable source issolar, daytime operation may begin at daybreak when the solar fieldfirst starts to receive sunlight and produce power. The control room mayautomatically recognize the power increase from the solar field andbegin the shutdown process for the gas turbines. Until the solar fieldhas reached “stated plant output” the gas turbines may remain online.After “stated plant output” has been reached by the solar field commandsare sent to from the control system to the hydrogen generator 120 tobegin hydrogen production. The hydrogen production process begins bysimultaneously opening cooling and feed water valves and activating thepumps associated with those functions. As power from the solar field 102continues to increase and drawdown on stored processed fresh waterbegins, the control room initiates reverse osmosis facility operations.All water storage tanks will be equipped with a float system that willmonitor storage volume. Reverse osmosis will continue until the storagetanks are full or there is insufficient power from the solar field tocontinue operations. If domestic water production is desired, the plantcan be optimized to run the reverse osmosis plant continuously toprovide water.

In the event of interruption of power production on the solar field dueto partly cloudy weather, the control room software recognizes the rateof decline and percent of total field output loss. At a certain point,the rate of decline and the limited remaining production will triggergas turbine start up to compensate for the loss of solar production. Theplant operator has the ability override the computer system in such anevent. In the event of continued intermittent loss of solar production,the plant operator has the ability to override software protocol andmaintain gas turbine production to prevent an excessive number of andshutdowns of the gas turbines, though in an embodiment, the system mayalso determine if the number of startups and shut downs is excessive,and keep the turbines operational or implement a more conservativecriteria (such as waiting for a sustained period of renewable energyoutput) before stopping the turbines. In an embodiment, the operator maybe aware, or the control system may be made aware, of weather eventsthat would cause a rapid decline in solar production compensating forthat condition by initiating gas turbine start up prior to loss of solarproduction. It is noted that the spin up time for most many turbines is6 to 8 minutes.

As noted above, the concepts described above may also be applied in apower plant using wind energy, hydro-power, geo-thermal power, or anyother suitable power source in place of solar energy. As such, if therenewable source is wind, then the control room may constantly monitorpower production from the wind farm, and supplement any loss ofproduction with power from the Gas Turbines.

An economic methodology may also be applied in the configuration of thesystem 100. According to an illustrative embodiment, the economic modelis based on an assumed 30 year plant life. Total costs are determined byadding the costs of all of the component parts of the plant. The cost ofthe renewable power source may be determined by the total number ofgenerating units to be installed. The total number of generating unitsto be installed is determined by the output of each panel divvied intothe total output needed. As an example, certain CPV solar panels produce30 KWh in direct sunlight, and therefore a plant requiring 5 megawattsof solar power would need 167 solar panels. Each such panel may cost$80,000 to produce and $10,000 to install, though prices may be flexibleand larger orders may receive a price break.

According to an illustrative embodiment, the cost of the gas turbines isdetermined by the number and model of the turbines used. A SiemensSGT-800 turbine, for example, may cost 25 million dollars installed.According to an illustrative embodiment, the cost of cogenerationturbines will also be based on number and type used. If, for example,Pratt & Whitney Turboden co-generation turbines are used, each unit willhave an installed cost of 17 million dollars.

According to an illustrative embodiment, a reverse osmosis plant has afixed cost of $2.72 per 1000 gallons, including maintenance. The fixedcost is simply multiplied by the number of gallons per day needed todetermine an overall cost for the facility to determine total cost.Storage may be considered variable and may be determined based on theamount of storage deemed necessary. For example, an assumed averagehydrogen storage cost of $0.07 per cubic foot of hydrogen and $1.00 pergallon of water can be used to derive costs. The cost of theelectrolyzers may be dependent on the demand for hydrogen production.The National Renewable Energy Lab Report from September 2009, forexample, estimated a cost of $800 per kilogram per day for hydrogenproduction. The estimated cost may be adjusted to reflect down time, andin an embodiment in which the electrolyzers are only expected to beactive for half a day, the estimate may be doubled to $1600 per kilogramto reflect the expected non-productive time. The balance of system costsincludes yard piping, the control room systems (including associatedhardware and software), and facility buildings. The yard piping is sitespecific but an estimated 150 dollars per lineal foot can be assumedwhich includes pumps and valves. The control room will consist of arobust computer system to monitor and control plant operations. Thissystem including software is roughly estimated to cost 2.5 milliondollars. The facility buildings are estimated to cost $150 per squarefoot which includes all internal machinery and piping.

Applying the foregoing assumptions, three separate economic modelsdescribe the potential income of the plant. The first is a model wherethe end user and grid prices differ. In this model the end user receivesa price break on the demanded continuous power and all other excesspower is sold to the grid at a constant rate. The second model has nodistinction between grid price and end user price. This model can alsobe represented as a straight sale to the grid. The last model type is astand-alone model where no excess power generated by the solar field issold. This model represents no grid connectivity and a fixed continuousdemand.

Three economic case studies are presented below. Each case study hasfollowing in common assumptions: location; overall continuous powerdemand; solar field size; plant equipment; hydrogen demand; and storagefield size. The only differences between the first three studies are themethod and price of sales, all capital costs remain constant. All modelsassume a continuous power demand of 55 MW, with a solar field size of450 MW. Each model also uses weather conditions from El Paso, Tex. asreported by NOAA. Due to El Paso's weather and location much more solarenergy is produced during the summer. This decreases total turbinedemand noticeable in those months. The following graph shows powergeneration potential. Total capital costs for all models are 1.494billion dollars. Lifetime maintenance costs of just over 100 milliondollars are projected, bringing the lifetime plant cost to 1.597 billiondollars.

Model 1—End User with Grid: The first model sells power to an end userat the rate of $0.06 per KWh and any excess power is sold to the grid ata rate of $0.075. In this model 604,000 MW of excess solar are sold tothe grid in an average year, while 482,000 MW are sold to the end user.This results in $45,334,180 a year in excess solar sales and $28,908,000a year from hydrogen plant sales. The income is not distributed evenlyover the year as the majority of excess solar sales come from May toAugust. The plant produces a total of 35.58 million megawatts over itslifespan with a total cost of 1.597 billion dollars this yields a$0.0490 cost per KW well within conventional generating costs.

Model 2—Grid Only: The second model assumes that a local utility isbuying all power produced at one fixed rate. In this model the powerproduced from the hydrogen plant as well as any excess solar power fromthe field is sold at a constant $0.075 per KWh. The amount of powergenerated by the plant and the solar field remain the same as the sizeof both remains unchanged. A total of 32,587,672 MW are produced overthe plant life yielding a total income of 2.44 billion dollars. As withmodel 1 profits are not evenly distrusted over the course of a yearfollowing the same pattern as Model 1. Price per KWh also remainsconstant with Model 1 at $0.049 per KWh

Model 2 is slightly more profitable than model one due to the increased0.015 increase in sales from the energy produced in the hydrogen plant.Models 2 yield a projected total profit of $846,106,000 or a 52% returnon initial investment.

Model 3—International Pricing: Model 3 is a variation on Model 2. Theonly difference is the sale price of the power. Model 3 is designed toreflect an international sales rate. Energy rates outside of the UnitedStates vary from $0.20 to $0.50. We estimated a conservative sale costof $0.15 per kw in this model. All other factors including the weatherfor El Paso, Tex. remain the same. As with Models 1 and 2 income variesfrom month to month at the rate described in Model 1. Total projectedincome per year is $162,938,000. Approximately 90 million is from excesssolar production, while 72 million is from hydrogen plant production. Alifetime 3.29 billion dollars in total revenues is expected over the 30year plant life. This is a 220% return on investment.

Model 4—Stand-alone: The standalone model differs from the other 3models in that the solar field has been sized to the absolute minimum toprovide enough hydrogen production for the shortest “average solar day”In this case 401 MW versus the 450 the other models had. Without excesssolar power sell back efficiency may be maximized and capital costsreduced as much as possible. This model is only suited for area with nogrid connectivity and assumes no excess power will be bought duringdaylight hours. It is entirely possible that depending on site locationsthat some excess power maybe sold however it is impossible to modelwithout a detailed use analysis report.

The total cost for the plant comes in at 1.363 billion dollars asopposed to 1.597 billion dollars for all other case studies. This is atotal of a 14.6% savings and brings the standalone cost down to $0A009per KWh. Sale price for the model is set at $0.125 which yields a totalincome of 1.806 billion dollars and a projected profit of 348 milliondollars.

It will be understood that the benefits and advantages described abovemay relate to one embodiment or may relate to several embodiments of theinvention. It will further be understood that reference to “an” itemrefers to one or more of those items.

What is claimed:
 1. A system for providing electric power to acommercial military or industrial user, the system comprising: arenewable energy power generator; a fuel-based power generator; ahydrogen generator electrically coupled to the renewable energy powergenerator; a water source coupled to the hydrogen generator to supplywater to the hydrogen generator; a hydrogen storage system fluidlycoupled to the hydrogen generator and the gas turbine generator; and acontrol system communicatively coupled to the renewable energy powergenerator and gas turbine generator.
 2. The system of claim 1, whereinthe renewable energy power generator is selected from the groupconsisting of a solar panel array, a wind farm, and a tidalhydroelectric power generator.
 3. The system of claim 1, wherein thefuel-based power generator comprises a gas turbine generator.
 4. Thesystem of claim 3, wherein the gas turbine generator comprises acogeneration system having a primary turbine generator, a heatexchanger, and a steam turbine generator.
 5. The system of claim 1,wherein the fuel-based power generator comprises a fuel cell.
 6. Thesystem of claim 1, wherein the hydrogen generator comprises a hydrogengeneration subsystem having a utility-scale electrolyzer, theutility-scale electrolyzer comprising a compressor for pressurizinghydrogen gas produced by the utility-scale electrolyzer.
 7. The systemof claim 6, wherein the hydrogen generator comprises a hydrogengeneration subsystem having a reverse osmosis subsystem for receivingunpurified water and providing purified water to the utility-scaleelectrolyzer.
 8. The system of claim 1, wherein: the control system isoperable to determine whether the power output from the renewable energypower generator is above a predetermined power output threshold; thecontrol system is operable to determine whether an amount of storedhydrogen in the hydrogen storage system is above a predeterminedhydrogen threshold; the control system is operable to divert power fromthe renewable energy power generator to a power grid when the poweroutput from the renewable energy power generator is above thepredetermined power output threshold and the amount of stored hydrogenin the hydrogen storage system is above the predetermined hydrogenthreshold; and the control system is operable to start the gas turbinegenerator when the power output from the renewable energy powergenerator is less than the predetermined power output threshold.
 9. Thesystem of claim 8, wherein the control system is operable to stop thegas turbine generator when the power output from the renewable energypower generator is greater than the predetermined power outputthreshold.
 10. The system of claim 9, wherein: the control system isoperable to determine whether a rate of change of power output from therenewable energy power generator is below a predetermined rate ofchange; and the control system is operable to stop the gas turbinegenerator when the power output rate of change of power output from therenewable energy power generator is below a predetermined rate ofchange.
 11. The system of claim 1, wherein: the control system isoperable to indicate to a user whether the power output from therenewable energy power generator is above a predetermined power outputthreshold; the control system is operable to indicate to a user whetheran amount of stored hydrogen in the hydrogen storage system is above apredetermined hydrogen threshold; the control system is operable todivert power from the renewable energy power generator to a power gridin response to a user initiated signal; and the control system isoperable to start the gas turbine generator in response to a userinitiated signal.
 12. A process for continuously generating electricpower for provision to a commercial military or industrial user, theprocess comprising: using a renewable energy power generator to generateenergy from a renewable energy power source; using a hydrogen fuel togenerate electrical energy; providing electric power to a hydrogengenerator from the renewable energy power generator; supplying water tothe hydrogen generator from a water source; and generating hydrogen gasfrom the water system using an electrolysis process using power from therenewable energy power generator and water from the water source; andstoring the hydrogen gas in a hydrogen storage system.
 13. The processof claim 12 comprising using a control system to initiate the step ofusing a hydrogen fuel to generate electrical energy.
 14. The process ofclaim 12, wherein using a renewable energy power generator to generateenergy from a renewable energy power source comprises using one of asolar power generator, a wind power generator, a geo-thermal powergenerator, and a hydro-power generator.
 15. The process of claim 12,wherein using a hydrogen fuel to generate electrical energy furthercomprises using a cogeneration system to generate electrical energy, thefuel cell having a gas turbine generator, a heat exchanger, and a lowtemperature steam turbine generator.
 16. The process of claim 12,wherein using a hydrogen fuel to generate electrical energy furthercomprises using fuel cell to generate electrical energy.
 17. The processof claim 12, further comprising: determining whether the power outputfrom the renewable energy power generator is above a predetermined poweroutput threshold; determining whether an amount of stored hydrogen inthe hydrogen storage system is above a predetermined hydrogen threshold;diverting power from the renewable energy power generator to a powergrid when the power output from the renewable energy power generator isabove the predetermined power output threshold and the amount of storedhydrogen in the hydrogen storage system is above the predeterminedhydrogen threshold; and initiating the step of using a hydrogen fuel togenerate electrical energy when the power output from the renewableenergy power generator is less than the predetermined power outputthreshold.
 18. The process of claim 12, further comprising: indicatingto a user whether the power output from the renewable energy powergenerator is above a predetermined power output threshold; indicating toa user whether an amount of stored hydrogen in the hydrogen storagesystem is above a predetermined hydrogen threshold; receiving a firstuser-generated command to divert power from the renewable energy powergenerator to a power grid; diverting power from the renewable energypower generator to the power grid in response to receiving the firstuser generated command; receiving a second user-generated command toinitiate the step of using a hydrogen fuel to generate electricalenergy; and initiating the step of using a hydrogen fuel to generateelectrical energy in response to receiving the second user-generatedcommand.
 19. The process of claim 12, wherein generating hydrogen gasfrom the water system using an electrolysis process using power from therenewable energy power generator and water from the water sourcecomprises compressing the produced hydrogen gas for storage to apressure of more than 400 psi.
 20. The process of claim 12, whereingenerating hydrogen gas from the water system using an electrolysisprocess using power from the renewable energy power generator and waterfrom the water source comprises using a reverse osmosis system to purifywater from the water source and providing the purified water to anelectrolyzer to produce hydrogen gas.